The present invention relates to an apparatus for processing baglike container blanks for use in a packaging machine for producing rectangular parallelepipedal containers filled with milk or like contents.
Apparatus of this type heretofore known include one which is adapted to process baglike container blanks each having a thermoplastic synthetic resin layer on each of its opposite surfaces by folding a pair of triangular ears flat while projecting the ears sidewise from the portion of each blank to be made into the bottom of a finished rectangular parallelepipedal container, and press-bonding the projected triangular ears to outer surface portions of the trunk wall of the container at the lateral sides thereof after folding the ears over the lateral side portions.
With reference to FIG. 8, each triangular ear E is press-bonded to the lateral side portion by fitting the container blank B around a pair of forming plates 11, 12 arranged at a distance from each other in parallel, and then pressing a press bonding member 13 against the ear E. The lateral side portion over which the ear E is folded is therefore subjected to the pressure and becomes damaged. Especially because this portion has a sealed seam S produced when the blank B is formed, the base portion of the seam S indicated by an arrow is liable to damage locally, with the resulting likelihood that a polyethylene layer forming the blank B will break to develop a pinhole at the base portion.